Alkylation with charge stock from isomerization and hydrogenation reactions

ABSTRACT

AN ALKYLATION FEEDSTOCK COMPRISING BUTENE-1, BUTENE-2, ISOBUTYLENE AND N-BUTANE IS FRACTIONATED TO PRODUCE STREAM WHICH ARE ISOMERIZED TO CONVERT THE BUTENE-1 TO BUTENE-2, OR WHICH ARE HYDROGENATED TO CONVERT THE ISOBUTYLENE TO ISOBUTENE. A PLURALITY OF STREAM ARE THUS DIREACTED TO ALKYLATION TO PROVIDE INCREASED YIELD OF ALKYLATE.

May 16, 1972 c. c. CHAPMAN ALKYLATION WITH CHARGE 5 TOOK FROMISOMERIZATION AND HYDROGENATION REACTIONS Filed July 15, 1970 N 7 I BNOZQ NOLLVNOLLDVEL-l E (/2, g m 5 v M 3 o o g :1: g 0

3NOZ wouvmouavaa N Z V 9 w .:z

Z Z Z O O 5 N N J z l- 2 mu 2% 9 ON m m g m l 5 v z z c g a N E fl o 2 IA I LL V v (D co *7 In EINOZ *7 NOliVNOliDVbL-J INVENTOR. c. c. CHAPMANv ATTORNEYS United States Patent Oflice 3,663,646 I ALKYLATION WITHCHARGE STOCK FROM ISQMERIZATION ,AND vI' IYDR OGENATION REACTIONS ,j ICharles C. Chapman, 'Bartlesville,"0kla.',assignor to Phillips PetroleumCompany Filed July 15, 1970, SenNo. 55,031

Int."Cl. C07c 3/50 U.S.'Cl. 260-6834 R -'5 Claims ABSTRACT OF THEDISCLOSURE An alkylation feedstock comprising butene-l, butene-2,isobutylene and n-butaue is fractionated to produce streams whichareisom'rized to convertthe butene-l to butene-2,'or which are hydrogenatedtoconvert'the isobutylene to isobutane. A plurality of streams are thusdirected to alkylation to provide increased yield of alkylate.

v This invention-pertains to thealkylation of hydrocarbons.

In-one of its more specific aspects, this invention pertains to thepreparation of feedstocks for alkylation.

Both hydrocarbon hydrogenation and hydroisomerization processes are wellknown and'hav'c been employed for some time in producing high octaneblending stocks for motor fuels. There has now been developed a processin which the two processes have been 'in'tegrated'to produce optimumfeedstocks for alkyl'ation. According to the method of this inventionthere is-pro vided a process for preparing a charge stock to analkylation unit from a feedstream comprising butene-l, butene-Z,isobutylene, isobutane and n-buta'rie in which a separation, orfractiouatiom'is made to produce stream 1'; containing 'isobutylene,butene-l, and isobutane and stream b containing butene-2 and n-butane;stream a is hydroisomerized to convert butene-l to butene-2 as productscontained in stream 6; meme is separated or fractionated to producestream d containing'the isobutylene and ,isobutane and stream acontainingbutene-Z; stream d ishydroiso'merized to produce stream 1, astream containingisobutene, and streamsb, e and fare charged-to analkylation unit. T

Accordingly, it' an object'of the present invention to produce optimumalkylation feedstocks The method of "this invention will be derstood ifexplained in conjunction withthe. attached figure which shows asimplified flow diagram of the process.

more easily un- 3,663,646 Patented May 16 1972 n-Pentane'.

About 49 metric tons per day of stream 5 is passed into the alkylationunit 2 through conduit 16, the balance of stream 5 being otherwisedisposed of. Stream 6 passes into the hydroisomerization unit 3 intowhich 0.51 metric ton per day'Bf hydrogen are introduced through conduit21. The product issuing from the hydroisomerization unit through conduit8 is passed into fractionation zone 7 through conduit 10. Depending uponthe availability of isobutane, as provided in the after-discussed stream30, it may be advantageous to split stream 8 into streams 9 and 10,stream 9 being introduced directly into the alkyla- 'tion unit. Whilethe invention is not meant to be so limited, it will be assumed hereinthat this procedure is followed. In this instance, compositions of thesestreams are as follows when employing conventional hydroisomerizationcatalysts and space velocities at a pressure of about 100 p.s.i.a. and acatalyst bed temperature of about 350 F.

Stream 10, passing into fractionation zone 7, is fractionated at apressure of about 95 p.s.i.a. at a top tower The principal conversionprocesses involved in the j method of this invention arehydroisomerization and bydrogenation. Both of these procedures,'togetherwith the intermediate separation, preferably fractionation, steps arewell known and any of the variety of such processes may be employed toeffect the process changes referred to. Hence, the details of thespecific conditions under which any of these processes are carried outneed not be recited.

Referring now to the attached drawing there is shown, introduced intofractionation zone 1 through conduit 4, a charge stock material. Fromfractionation zone 1, two streams are recovered, one through overheadconduit 6 and one through bottoms conduit 5, assuming the fractionationto be conducted at about 95 p.s.i.a., at a bottorn tower temperature ofabout 150 F. and a top tower temperature of about 127 F. (All streamsdiscussed herein are designated with the same number as that conduitthrough which they are passed. All stream quantities are given in metrictons per day.) Stream quantities around fractionation zone 1 are asfollows:

temperature of about F. and a bottom tower temperature of about 146 F.,to produce a bottoms product through conduit 11 and an overhead streamthrough conduit 12.'Ana1ysis' of these two streams into which stream 10is separated is as follows:

Stream 11 is introduced into the alkylation unit whereas stream 12, and4.09 metric tons per day of hydrogen added through conduit 22, areintroduced into hydrogenation unit 13. This hydrogenation unit will beoperated under any of the conventional operating conditions with any ofthe commercially available catalysts to hydrogenate, primarily, theunsaturated butenes to butane. The

product from the hydrogenation unit is conducted through Stream N o.

Product from Overhead from hydrogena- Added fractionation Identificationtion Zone 13 isobutane Zone 17 Propylene 3. 26

Propane 15. 18. 26 Isobuty n-Pentane As a result, there are introducedinto alkylation zone 2, and into which is equipped with recoveryfacilities for the separation of the alkylate product, a plurality ofstreams which are directed to maximizing the yield of alkylate from theoriginal charge stock.

The alkylation process is conventional within the art, for example,being operated at a pressure of about 100 p.s.i.a. and at a temperatureof 100 F., employing hydrofluoric acid in an amount about 1 volume ofacid per volume of hydrocarbon, the isobutane olefin mole ratio beingabout 10 to 1. Under these conditions, the propane stream, n-butanestream and alkylate product recovered through conduits 18, 19, and 20,respectively, have the analyses as shown below, in metric tons per day.

Stream N0.

Propane Butane cut from out from alkylation alkylation AlkylateIdentification unit unit product Propane 23. 45 Isobutane.. 0. 22

It will be evident from the foregoing that various modifications can bemade to the method of this invention. Such, however, are considered asbeing within the scope of the invention.

What is claimed is:

1. A method of preparing a charge stock to an alkylation from afeed-stream comprising butene-l, butene-Z, isobutylene, isobutane andn-butane which comprises (a) separating said feedstream into a first anda second stream, a principal portion of said isobutylene, butene-l andisobutane being contained in said first stream and a principal portionof said butene-Z and said n-butane being contained in said secondstream;

(b) converting a principal portion of the butene-l of said first streamto butene-Z to produce a third stream containing principallyisobutylene, butene-2 and isobutane;

(c) separating said third stream into a fourth and a fifth stream, aprincipal portion of said isobutylene and isobutane being contained insaid fourth stream and a principal portion of said butene-2 beingcontained in said fifth stream;

(d) converting a principal portion of the isobutylene to said fourthstream to isobutane and to produce a sixth stream containing principallyisobutane; and,

(e) introducing said second, fifth and sixth streams into an alkylationunit.

2. The method of claim 1 in which a portion of said third stream and astream comprising principally isobutane are introduced into saidalkylation unit.

3. The method of claim 2 in which the separating of said feedstream intoa first and second stream and separating of said third stream into afourth and fifth stream are done by fractionation.

4. The method of claim 2 in which a principal portion of the butene-l ofsaid first stream is converted to butene- 2 by isomerization.

5. The method of claim 2 in which a principal portion of the isobutyleneof said fourth stream is converted to isobutane by hydrogenation.

References Cited UNITED STATES PATENTS 2,396,853 3/1946 Jones 260-6834 R2,450, 59 9/1948 Frey 260-68349 2,502,015 3/1950 Matuszak 260683.492,591,367 4/1952 McAllister 260683.49 2,594,343 4/1952 Pines 260683.492,820,074 1/1958 Pines 260-683.49

DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant ExaminerU.S. Cl. X.R.

